Late Cretaceous mesothermal-hyperthermal molybdenum-beryllium deposit, hosted in Upper Jurassic volcanic rocks that are intruded by a concealed biotite granite.

The Dawan Be(Mo) deposit in the northeastern Fujian Province occurs within the Late Mesozoic volcanic rocks along the southeast coast belt and the east of the Fu'an-Nanjing fault zone. In the deposit area, an extensional fracture network is well developed, NE-trending fractures serve as the primary ore-controlling structures. The lithological units consist of the Late Jurassic Nanyuan Formation volcanic sequence (predominantly tuff and rhyolite), along with minor occurrences of porphyritic fine-grained granite, granite porphyry dykes, and microcrystalline diorite veins. The northeast-trending quartz dykes constitutes the main ore body and are distributed within the structural fractures of tuff and rhyolite. There are two type occurrence of quartz dykes. One type is horizontally parallel to the granite, while the other is nearly vertically distributed within the upper part of the Nanyuan Formation tuff.

he orebodies are distributed along the contact zones between granite and volcaniclastic rocks of the Nanyuan Formation. Based on their distribution, the orebodies are in two different occurrences: (1) veins that are 100–700 m long and up to 2.5 m thick, which occur in steeply inclined fractures in tuff that strike 25–65° and dip 75–85°SE; and (2) veins parallel to the contact between the granite and tuff, or in the granite, which are 300–600 m long and ∼ 2 m thick. In the steeply inclined veins, the Be orebodies occur mainly on both sides of the Mo orebodies.

The main ore is helvine.

Other Regions, Features and Areas containing this locality

References